With the development of the Ethernet towards the multi-service bearer, and particularly, higher and higher requirements on the reliability and the real-time of the network from a plurality of services, the Ethernet widely uses the ring networking so as to improve the reliability. During the protection in the ring network, fast protection switch is generally required, and the time of the protection switch should be below 50 ms. Currently, this kind of fast protection switch techniques includes RFC3619 of the Internet Engineering Task Force (IETF), G.8032 of the International Telecommunication Union, and so on.
The existing multi-ring Ethernet is as shown in FIG. 1, wherein nodes S1 to S6 are all Ethernet switching devices, the network B and the node S2 are connected, the network A and the node S5 are connected, and there are four physical paths for communicating between the network A and the network B, including: the network A←→the node S5←→the node S3←→the node S2←→the network B, the network A←→the node S5←→the node S3←→the node S4←→the node S1←→the node S2←→the network B, the network A←→the node S5←→the node S6←→the node S4←→the node S3←→the node S2←→the network B, and the network A←→the node S5←→the node S6←→the node S4←→the node S1←→the node S2←→the network B.
When applying the protection technique of the multi-ring Ethernet, a Ring and a Sub-Ring are usually used, wherein a Ring is a complete Ethernet ring, and a Sub-Ring is an Ethernet ring connected with other rings or networks through an Interconnection Node. The Interconnection Node is a common node simultaneously belonging to two or more Ethernet rings, and the Interconnection Node also can be called as a shared node. As shown in FIG. 2, it includes one Ring and one Sub-Ring, wherein Ring1 is the Ring, and Ring2 is the Sub-Ring. Ring1 includes nodes S1, S2, S3 and S4, and includes links <S1, S2>, <S2, S3>, <S3, S4> and <S4, S1>; Ring2 includes nodes S3, S5, S6 and S4, and includes links <S3, S5>, <S5, S6>, and <S6, S4>. It should be emphasized that the link <S3, S4> belongs to Ring1 rather than Ring2. Nodes S3 and S4 are the interconnection nodes of Ring1 and Ring2. The 33 port of the node S3 and the 43 port of the node S4 belong to Ring2, which are called as access ports.
In the case there is no failure in the ring network, a path, which is called as a ring protection link or constantly blocked path, is needed to block the forwarding of data message to prevent ring formation, and the switch between the primary path and the protection path is participated through the ring protection link in the ring. The node owning the ring protection link is called as a ring protection link control node. As shown in FIG. 2, in Ring 1, node S4 is the ring protection link control node, and the link directly connected to port 41 of the node S4 is the ring protection link of Ring 1. In Ring 2, node S5 is the ring protection link control node, and the link directly connected to port 52 of the node S5 is the ring protection link of Ring 2.
When links of the multi-ring Ethernet are all in a good condition, i.e., links are in a normal state, the ring protection link control nodes of the Ring and Sub-Ring block protection data forwarding function of the their secondary ports to prevent the protection data from being repeatedly forwarded and forming broadcasting storm. As shown in FIG. 2, the node S4 in Ring1 blocks the protection data forwarding function of the port 41, the node S5 in Ring2 blocks the protection data forwarding function of the port 52, and the communication path between the network B and the network A is the network B←→the node S2←→the node S3←→the node S5←→the network A.
When a failure occurs in the link of the multi-ring Ethernet, and if the failure link is not the protection link, then the ring protection link control node opens the protection data forwarding function of the secondary port, and each node should update the address forwarding table, and the communication between networks is transmitted based on the new path. As shown in FIG. 3, a failure occurs in the link <S2, S3> of Ring1; nodes S2 and S3 respectively block the data forwarding functions of ports 22 and 31 after detecting the link failure, and notify other nodes that the failure occurs in the link; the node S4 is a ring protection link control node, and the node S4 opens the protection data forwarding function of the port 41 after receiving the failure notification; besides, each node on Ring1 should also update the address forwarding table, and the new communication path between the network B and the network A is the network B←→the node S2←→the node S1←→the node S4←→the node S3←→the node S5←→the network A.
When the link of the multi-ring Ethernet recovers, the recovering switch is performed, and the network transmission recovers to the transmission path of the normal state. Since the path changes, the nodes also needs to update the address forwarding table.
Although the related art solves the protection problem of the multi-ring Ethernet very well, there still lacks a method for effectively managing the topology of the multi-ring Ethernet, used for discovering information of the node locations, topology statuses, whether the path can be reached and so on in the whole multi-ring Ethernet.